1. Field of the Invention
The present invention relates to a novel polymerizable compound having functional groups different in reactivity, a process for producing the same, and a polymer obtained from a composition containing the polymerizable compound. Especially, the present invention achieves effectively enhancement in characteristics of such as formability, heat-resistance, mechanical properties and electric properties of the polymers, rendering the polymers useful as insulating materials for electric apparatuses and protective coating materials.
2. Description of Related Art
Conventional thermosetting resin compositions having excellent formability, heat-resistance and mechanical properties to be used for insulating layers in multi-layer printed circuit boards contain as components polymers having three dimensionally cross-linkable functional groups in side chains. For example, Japanese Patent KOKAI (Laid-open) No. Sho 63-56548 discloses poly(p-hydroxystyrene) derivatives having alkenyl or alkenoyl groups in side chains. In order to produce such polymers having the functional groups in side chains, a process where introduction of the functional groups into the side chains can be made by reacting the hydroxyl groups of the poly(p-hydroxystyrene) with alkenyl chloride or alkenoyl chloride is known. These polymer precursors to be used as starting materials for production of the setting polymers are considered to have hydroxyl, carboxyl, amino groups or the like introduced in side chains. Polymerization of these addition-polymerizable monomers having such functional groups requires protection of the functional groups as reported in Proceedings, KOBUNSHI GAKKAI, Vol. 39, No. 6, pp. 1730-1732.
Compounds having functional groups different in reactivity are known as Japanese Patent Publication, No. Hei 3-43287 discloses multi-functional compounds which are produced by introducing a maleimide derivative into a styrene derivative residue, one of which, N-(p-vinylphenyl) maleimide is clarified for its polymerization reactivity. It is known that when an anionic initiator, alkali metal t-butoxyde is used, the maleimide groups polymerize, while a cationic initiator, BF.sub.3 O(CH.sub.2 CH.sub.3).sub.2 is used, the vinyl groups polymerize as disclosed in Proceedings, KOBUNSHI GAKKAI, Vol. 39, No. 2, p. 266.
However, the introduction of reactive functional groups into side chains limits the processes therefor to such that ester functional groups such as acrylate, methacrylate, and the like capable of being readily introduced are introduced by using chlorides, or that amino groups are maleimidized. For this reason, in order to obtain cured products having a combination of necessitate heat resistance, mechanical characteristics and formability, one resin has been needed to be blended with other ones for supplementing some properties, of which the resin alone is devoid. This causes a problem of generation of crackes and the like due to phase separation, which leads to a difficulty in determination of curing conditions for production of homogeneous cured resin products.